Predictive Services

Following the 1998 fire season, TFS established the Predictive Services Department as a permanently staffed unit to provide short and long-term forecasts and analysis. The program produces information and products that are utilized at the national, state and local level by firefighters, election officials and public administrators. Most of the products (daily fire danger, drought indices, fuel dryness) have been developed as automated, online and publically available resources through a partnership with the TAMU AgriLife Spatial Sciences Laboratory.

Assessment and Monitoring

TFS continually analyzes current and predicted weather conditions, wildfire occurrence, and the presence and availability of vegetative fuels throughout the year to maintain a continual assessment of wildfire risk at the state, regional and local level. Utilizing this information, agency staff develop daily and seasonal forecasts to assist the state and local government entities in preparing for and responding to periods of elevated fire danger or fire seasons.

Wildfire occurrence and cause are tracked by an online Fire Department Fire Reporting System. This is a voluntary system available to all fire departments across the state. This information is shared with Texas A&M Forest Service prevention staff, local cooperators, elected officials and the public. Wildfire occurrence information is also used to guide TFS fire planning and preparedness, and response efforts.

Conditions of wildland fuels are observed and used to calculate and predict fire behavior. Each region of the state contains a dominant fuel type - grasses, brush and trees - that TFS must consider when assessing risk. Factors such as the level of drought; percentage of rainfall; how quickly the grasses, brush and trees dry out; and how readily they will ignite and burn are all calculated and considered.

TFS predictive service officials utilize updated Texas Wildfire Risk Assessment statistics in preparation for the next fire siege. This information allows TFS to provide qualitative, scientific data to show Legislators and the general public how the wildland fire landscape is changing across the state.

Fire Danger

Fire danger ratings describe conditions that reflect the potential, over a large area, for a fire to ignite, spread and require suppression action. Fire danger rating compares past, current, and forecasted weather. Fire danger rating is a tool designed to aid fire managers in making day-to-day decisions on preparedness, suppression readiness, prevention activities, and dispatch level needs.

BURNING INDEX

SFP Matrix Components -
There are three components to the SFP decision matrix. The Fuel Dryness Level represents composite fuel dryness as measured by the energy release component (ERC). The Fire Weather Level is a snapshot of the daily fire weather as measured by the burning index (BI). The combination of Fuel Dryness and Fire Weather produces an adjective rating for Significant Fire Potential (SFP).

ERC is a National Fire Danger Rating System (NFDRS) index that can be used to gauge the composite fuel dryness across the landscape. ERC incorporates all the dead and live fuel moisture inputs. ERC is often called a buildup index as it remembers and considers inputs from the previous 7 days.

Burning Index is also a NFDRS composite index that is used to represent the daily fire weather. BI does not have a memory of previous inputs as it resets each day. Burning index inputs are weighted heavily to windspeed and 1-hour fuel moisture providing a daily snapshot of fire weather.
The adjective SFP rating uses descriptors from low to very high to rank the potential for significant fire activity. The matrix is a simple 4 tier matrix that places the lowest potential in the top left corner and the highest potential in the bottom right corner. The four levels of Fuel Dryness and Fire Weather are divided by using climatological breakpoints of ERC and BI. Climatological or percentile breakpoints have proven to be reliable thresholds for predicting levels of fire activity. Most of us have referred to or heard reference of increased fire potential when ERC values have reached the 90th percentile. The four levels for both Fuel Dryness and Fire Weather use the following percentile or climatological breakpoints.

ENERGY RELEASE COMPONENT

BURNING INDEX

The energy release component (ERC) is a calculated output of the national fire danger rating system (NFDRS). The ERC is a number related to the available energy (BTU) per unit area (square foot) within the flaming front at the head of a fire. The ERC is considered a composite fuel moisture index as it reflects the contribution of all live and dead fuels to potential fire intensity. As live fuels cure and dead fuels dry, the ERC will increase and can be described as a build-up index. The ERC has memory. Each daily calculation considers the past 7 days in calculating the new number. Daily variations of the ERC are relatively small as wind is not part of the calculation.

The ERC relates well to the condition of the fuels. Fire managers and planners have found that the ERC can be used as a decision tool to prepare for an approaching fire season or it can be used as a tool for daily staffing when used in combination with other NFDRS components such as 100-hr fuel moisture or the burning index (bi). Tracking the ERC and other NFDRS components through the season and on a daily basis will increase the situational awareness of wildland firefighters.

ERC MAPS

ERC SEASONAL GRAPHS

Fuels are always gaining or losing moisture. Dead fuel moisture responds solely to ambient environmental conditions and is critical in determining fire potential. Dead fuel moistures are classified by time lag and is proportional to its diameter and is loosely defined as the time is takes a fuel particle to reach 2/3's of its way to equilibrium with its local environment. Dead fuels in the national fire danger rating system fall into four classes.

• 10-hour (1/4"-1" diameter): lower 10-hour fuel moisture provides guidance toward an earlier and later burn period. When forecast 10-hour fuel moisture percentiles are at or the below the 25th percentile, that is a good indicator of poor overnight relative humidity recoveries and increased availability of cured grasses.

Monitoring live fuel moisture is important to track and identify when canopy fuel is becoming more receptive to burning, increasing the resistance to control of wildfire. The predictive services department conducts monthly live fuel sampling in high risk fuel species across the state. Results are posted on the national live fuel sampling database.

FUEL DRYNESS

LIVE FUEL SAMPLING

REFERENCE

Weather plays a vital role in the fire environment toward fire potential and fire behavior. Firefighters and fire management staff are responsible for keeping up with current and forecast weather conditions. The predicative services department maintains an important partnership with the national weather service toward by collaborating and communicating burning conditions.

TEXAS CRITICAL THRESHOLDS

POCKET CARDS

Fire behavior is the site specific, description of an existing fire in a given time and space. Fire behavior describes the movement (rate of area increase), intensity (flame length), and indicators of rapid combustion (spotting, crowning, and fire whirls) of that fire. It is expressed as real time or predicted conditions for ongoing fires. For example, the flame length is 4 to 5 feet.

FIRE BEHAVIOR

Drought implies an increased availability of dead and live fuels that will contribute to combustion. Increased fuel loading will increase fire intensity, increase the rate of spread and generally increase a wildfire's resistance to control. These tools are designed to monitor changes in precipitation deficits and identify emerging dryness in the state.